To Ensoul a roll

You can ensoul your dice for greater effects. Each Soul’s Dice can be spent to change the result of any single die (D6) to a 6 (6!), guaranteeing a critical success. However, each roll may only be modified once, and the use of a Soul’s Dice must be declared before the roll is done. You can only modify dice that are to be rolled.

Soul Dice are not rolled; they are simply removed from the Soul Pool.